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張 旭

JSON Web Token Introduction - jwt.io - 0 views

  • a stateless authentication mechanism as the user state is never saved in server memory
  • In authentication, when the user successfully logs in using their credentials, a JSON Web Token will be returned and must be saved locally (typically in local storage, but cookies can be also used), instead of the traditional approach of creating a session in the server and returning a cookie.
  • ser agent should send the JWT, typically in the Authorization header using the Bearer schema.
  • ...2 more annotations...
  • It doesn't matter which domains are serving your APIs, so Cross-Origin Resource Sharing (CORS) won't be an issue as it doesn't use cookies.
  • WT and SAML tokens can use a public/private key pair in the form of a X.509 certificate for signing.
張 旭

elabs/pundit: Minimal authorization through OO design and pure Ruby classes - 0 views

  • The class implements some kind of query method
  • Pundit will call the current_user method to retrieve what to send into this argumen
  • put these classes in app/policies
  • ...49 more annotations...
  • in leveraging regular Ruby classes and object oriented design patterns to build a simple, robust and scaleable authorization system
  • map to the name of a particular controller action
  • In the generated ApplicationPolicy, the model object is called record.
  • record
  • authorize
  • authorize would have done something like this: raise "not authorized" unless PostPolicy.new(current_user, @post).update?
  • pass a second argument to authorize if the name of the permission you want to check doesn't match the action name.
  • you can chain it
  • authorize returns the object passed to it
  • the policy method in both the view and controller.
  • have some kind of view listing records which a particular user has access to
  • ActiveRecord::Relation
  • Instances of this class respond to the method resolve, which should return some kind of result which can be iterated over.
  • scope.where(published: true)
    • 張 旭
       
      我想大概的意思就是:如果是 admin 可以看到全部 post,如果不是只能看到 published = true 的 post
  • use this class from your controller via the policy_scope method:
  • PostPolicy::Scope.new(current_user, Post).resolve
  • policy_scope(@user.posts).each
  • This method will raise an exception if authorize has not yet been called.
  • verify_policy_scoped to your controller. This will raise an exception in the vein of verify_authorized. However, it tracks if policy_scope is used instead of authorize
  • need to conditionally bypass verification, you can use skip_authorization
  • skip_policy_scope
  • Having a mechanism that ensures authorization happens allows developers to thoroughly test authorization scenarios as units on the policy objects themselves.
  • Pundit doesn't do anything you couldn't have easily done yourself. It's a very small library, it just provides a few neat helpers.
  • all of the policy and scope classes are just plain Ruby classes
  • rails g pundit:policy post
  • define a filter that redirects unauthenticated users to the login page
  • fail more gracefully
  • raise Pundit::NotAuthorizedError, "must be logged in" unless user
  • having rails handle them as a 403 error and serving a 403 error page.
  • config.action_dispatch.rescue_responses["Pundit::NotAuthorizedError"] = :forbidden
  • with I18n to generate error messages
  • retrieve a policy for a record outside the controller or view
  • define a method in your controller called pundit_user
  • Pundit strongly encourages you to model your application in such a way that the only context you need for authorization is a user object and a domain model that you want to check authorization for.
  • Pundit does not allow you to pass additional arguments to policies
  • authorization is dependent on IP address in addition to the authenticated user
  • create a special class which wraps up both user and IP and passes it to the policy.
  • set up a permitted_attributes method in your policy
  • policy(@post).permitted_attributes
  • permitted_attributes(@post)
  • Pundit provides a convenient helper method
  • permit different attributes based on the current action,
  • If you have defined an action-specific method on your policy for the current action, the permitted_attributes helper will call it instead of calling permitted_attributes on your controller
  • If you don't have an instance for the first argument to authorize, then you can pass the class
  • restart the Rails server
  • Given there is a policy without a corresponding model / ruby class, you can retrieve it by passing a symbol
  • after_action :verify_authorized
  • It is not some kind of failsafe mechanism or authorization mechanism.
  • Pundit will work just fine without using verify_authorized and verify_policy_scoped
  •  
    "Minimal authorization through OO design and pure Ruby classes"
張 旭

Warnings, Notes, & Tips - 0 views

  • AS3 manages topology records globally in /Common, it is required that records only be managed through AS3, as it will treat the records declaratively.
  • If a record is added outside of AS3, it will be removed if it is not included in the next AS3 declaration for topology records (AS3 completely overwrites non-AS3 topologies when a declaration is submitted).
  • using AS3 to delete a tenant (for example, sending DELETE to the /declare/<TENANT> endpoint) that contains GSLB topologies will completely remove ALL GSLB topologies from the BIG-IP.
  • ...12 more annotations...
  • When posting a large declaration (hundreds of application services in a single declaration), you may experience a 500 error stating that the save sys config operation failed.
  • Even if you have asynchronous mode set to false, after 45 seconds AS3 sets asynchronous mode to true (API swap), and returns an async response.
  • When creating a new tenant using AS3, it must not use the same name as a partition you separately create on the target BIG-IP system.
  • If you use the same name and then post the declaration, AS3 overwrites (or removes) the existing partition completely, including all configuration objects in that partition.
  • use AS3 to create a tenant (which creates a BIG-IP partition), manually adding configuration objects to the partition created by AS3 can have unexpected results
  • When you delete the Tenant using AS3, the system deletes both virtual servers.
  • if a Firewall_Address_List contains zero addresses, a dummy IPv6 address of ::1:5ee:bad:c0de is added in order to maintain a valid Firewall_Address_List. If an address is added to the list, the dummy address is removed.
  • use /mgmt/shared/appsvcs/declare?async=true if you have a particularly large declaration which will take a long time to process.
  • reviewing the Sizing BIG-IP Virtual Editions section (page 7) of Deploying BIG-IP VEs in a Hyper-Converged Infrastructure
  • To test whether your system has AS3 installed or not, use GET with the /mgmt/shared/appsvcs/info URI.
  • You may find it more convenient to put multi-line texts such as iRules into AS3 declarations by first encoding them in Base64.
  • no matter your BIG-IP user account name, audit logs show all messages from admin and not the specific user name.
張 旭

AskF5 | Manual Chapter: Working with Partitions - 0 views

  • During BIG-IP® system installation, the system automatically creates a partition named Common
  • An administrative partition is a logical container that you create, containing a defined set of BIG-IP® system objects.
  • No user can delete partition Common itself.
  • ...9 more annotations...
  • With respect to permissions, all users on the system except those with a user role of No Access have read access to objects in partition Common, and by default, partition Common is their current partition.
  • The current partition is the specific partition to which the system is currently set for a logged-in user.
  • A partition access assignment gives a user some level of access to the specified partition.
  • assigning partition access to a user does not necessarily give the user full access to all objects in the partition
  • user account objects also reside in partitions
  • when you first install the BIG-IP system, every existing user account (root and admin) resides in partition Common
  • the partition in which a user account object resides does not affect the partition or partitions to which that user is granted access to manage other BIG-IP objects
  • the object it references resides in partition Common
  • a referenced object must reside either in the same partition as the object that is referencing it
張 旭

- 0 views

  • A fast-forward merge can happen when the current branch has no extra commits compared to the branch we’re merging.
  • With a no-fast-forward merge, Git creates a new merging commit on the active branch.
  • We can manually remove the changes we don't want to keep, save the changes, add the changed file again, and commit the changes
  • ...14 more annotations...
  • A git rebase copies the commits from the current branch, and puts these copied commits on top of the specified branch.
  • The branch that we're rebasing always has the latest changes that we want to keep!
  • A git rebase changes the history of the project as new hashes are created for the copied commits!
  • Rebasing is great whenever you're working on a feature branch, and the master branch has been updated.
  • An interactive rebase can also be useful on the branch you're currently working on, and want to modify some commits.
  • A git reset gets rid of all the current staged files and gives us control over where HEAD should point to.
  • A soft reset moves HEAD to the specified commit (or the index of the commit compared to HEAD)
  • Git should simply reset its state back to where it was on the specified commit: this even includes the changes in your working directory and staged files!
  • By reverting a certain commit, we create a new commit that contains the reverted changes!
  • Performing a git revert is very useful in order to undo a certain commit, without modifying the history of the branch.
  • By cherry-picking a commit, we create a new commit on our active branch that contains the changes that were introduced by the cherry-picked commit.
  • a fetch simply downloads new data.
  • A git pull is actually two commands in one: a git fetch, and a git merge
  • git reflog is a very useful command in order to show a log of all the actions that have been taken
張 旭

How to Write a Git Commit Message - 1 views

  • a well-crafted Git commit message is the best way to communicate context about a change to fellow developers (and indeed to their future selves).
  • A diff will tell you what changed, but only the commit message can properly tell you why.
  • a commit message shows whether a developer is a good collaborator
  • ...22 more annotations...
  • a well-cared for log is a beautiful and useful thing
  • Reviewing others’ commits and pull requests becomes something worth doing, and suddenly can be done independently.
  • Understanding why something happened months or years ago becomes not only possible but efficient.
  • how to write an individual commit message.
  • Markup syntax, wrap margins, grammar, capitalization, punctuation.
  • What should it not contain?
  • issue tracking IDs
  • pull request numbers
  • The seven rules of a great Git commit message
  • Use the body to explain what and why vs. how
  • Use the imperative mood in the subject line
  • it’s a good idea to begin the commit message with a single short (less than 50 character) line summarizing the change, followed by a blank line and then a more thorough description.
  • forces the author to think for a moment about the most concise way to explain what’s going on.
  • If you’re having a hard time summarizing, you might be committing too many changes at once.
  • shoot for 50 characters, but consider 72 the hard limit
  • Imperative mood just means “spoken or written as if giving a command or instruction”.
  • Git itself uses the imperative whenever it creates a commit on your behalf.
  • when you write your commit messages in the imperative, you’re following Git’s own built-in conventions.
  • A properly formed Git commit subject line should always be able to complete the following sentence: If applied, this commit will your subject line here
  • explaining what changed and why
  • Code is generally self-explanatory in this regard (and if the code is so complex that it needs to be explained in prose, that’s what source comments are for).
  • there are tab completion scripts that take much of the pain out of remembering the subcommands and switches.
張 旭

CertSimple | An nginx config for 2017 - 0 views

  • HAProxy can't terminate a HTTP/2 connection itself.
  • a server OS which includes OpenSSL 1.02 to have ALPN.
  • a new nginx (anything newer than 1.9.5 supports HTTP/2)
  • ...6 more annotations...
  • we like HTTPS/non-www since HTTPS is needed for current browsers and non-www is short.
  • visit the Mozilla TLS Generator to get the latest cipher suites and TLS versions
  • add the necessary headers for GeoIP and proper logging.
  • HTML5 SSE simpler than websockets
  • nginx -t
  • Scan your site with SSL Labs scan
張 旭

Rate Limits - Let's Encrypt - Free SSL/TLS Certificates - 0 views

  • If you have a lot of subdomains, you may want to combine them into a single certificate, up to a limit of 100 Names per Certificate.
  • A certificate with multiple names is often called a SAN certificate, or sometimes a UCC certificate
  • The main limit is Certificates per Registered Domain (20 per week).
  • ...12 more annotations...
  • A certificate is considered a duplicate of an earlier certificate if they contain the exact same set of hostnames, ignoring capitalization and ordering of hostnames.
  • We also have a Duplicate Certificate limit of 5 certificates per week.
  • a Renewal Exemption to the Certificates per Registered Domain limit.
  • The Duplicate Certificate limit and the Renewal Exemption ignore the public key and extensions requested
  • You can issue 20 certificates in week 1, 20 more certificates in week 2, and so on, while not interfering with renewals of existing certificates.
  • Revoking certificates does not reset rate limits
  • If you’ve hit a rate limit, we don’t have a way to temporarily reset it.
  • get a list of certificates issued for your registered domain by searching on crt.sh
  • Revoking certificates does not reset rate limits
  • If you have a large number of pending authorization objects and are getting a rate limiting error, you can trigger a validation attempt for those authorization objects by submitting a JWS-signed POST to one of its challenges, as described in the ACME spec.
  • If you do not have logs containing the relevant authorization URLs, you need to wait for the rate limit to expire.
  • having a large number of pending authorizations is generally the result of a buggy client
張 旭

Custom Resources | Kubernetes - 0 views

  • Custom resources are extensions of the Kubernetes API
  • A resource is an endpoint in the Kubernetes API that stores a collection of API objects of a certain kind
  • Custom resources can appear and disappear in a running cluster through dynamic registration
  • ...30 more annotations...
  • Once a custom resource is installed, users can create and access its objects using kubectl
  • When you combine a custom resource with a custom controller, custom resources provide a true declarative API.
  • A declarative API allows you to declare or specify the desired state of your resource and tries to keep the current state of Kubernetes objects in sync with the desired state.
  • Custom controllers can work with any kind of resource, but they are especially effective when combined with custom resources.
  • The Operator pattern combines custom resources and custom controllers.
  • the API represents a desired state, not an exact state.
  • define configuration of applications or infrastructure.
  • The main operations on the objects are CRUD-y (creating, reading, updating and deleting).
  • The client says "do this", and then gets an operation ID back, and has to check a separate Operation object to determine completion of the request.
  • The natural operations on the objects are not CRUD-y.
  • High bandwidth access (10s of requests per second sustained) needed.
  • Use a ConfigMap if any of the following apply
  • You want to put the entire config file into one key of a configMap.
  • You want to perform rolling updates via Deployment, etc., when the file is updated.
  • Use a secret for sensitive data, which is similar to a configMap but more secure.
  • You want to build new automation that watches for updates on the new object, and then CRUD other objects, or vice versa.
  • You want the object to be an abstraction over a collection of controlled resources, or a summarization of other resources.
  • CRDs are simple and can be created without any programming.
  • Aggregated APIs are subordinate API servers that sit behind the primary API server
  • CRDs allow users to create new types of resources without adding another API server
  • Defining a CRD object creates a new custom resource with a name and schema that you specify.
  • The name of a CRD object must be a valid DNS subdomain name
  • each resource in the Kubernetes API requires code that handles REST requests and manages persistent storage of objects.
  • The main API server delegates requests to you for the custom resources that you handle, making them available to all of its clients.
  • The new endpoints support CRUD basic operations via HTTP and kubectl
  • Custom resources consume storage space in the same way that ConfigMaps do.
  • Aggregated API servers may use the same storage as the main API server
  • CRDs always use the same authentication, authorization, and audit logging as the built-in resources of your API server.
  • most RBAC roles will not grant access to the new resources (except the cluster-admin role or any role created with wildcard rules).
  • CRDs and Aggregated APIs often come bundled with new role definitions for the types they add.
張 旭

手动安装 Prometheus · 从 Docker 到 Kubernetes 进阶手册 - 1 views

  • 参数storage.tsdb.path指定了 TSDB 数据的存储路径、通过storage.tsdb.retention设置了保留多长时间的数据,还有下面的web.enable-admin-api参数可以用来开启对 admin api 的访问权限,参数web.enable-lifecycle非常重要,用来开启支持热更新的,有了这个参数之后,prometheus.yml 配置文件只要更新了,通过执行localhost:9090/-/reload就会立即生效,所以一定要加上这个参数。
  • Prometheus 由多个组件组成,但是其中许多组件是可选的: Prometheus Server:用于抓取指标、存储时间序列数据 exporter:暴露指标让任务来抓 pushgateway:push 的方式将指标数据推送到该网关 alertmanager:处理报警的报警组件 adhoc:用于数据查询
  • scrape_configs 用于控制 prometheus 监控哪些资源。
  • ...6 more annotations...
  • prometheus 通过 HTTP 的方式来暴露的它本身的监控数据
  • prometheus 默认会通过目标的/metrics路径采集 metrics
  • 需要配置 rbac 认证,因为我们需要在 prometheus 中去访问 Kubernetes 的相关信息
  • 要获取的资源信息,在每一个 namespace 下面都有可能存在,所以我们这里使用的是 ClusterRole 的资源对象,值得一提的是我们这里的权限规则声明中有一个nonResourceURLs的属性,是用来对非资源型 metrics 进行操作的权限声明
  • 添加一个securityContext的属性,将其中的runAsUser设置为0,这是因为现在的 prometheus 运行过程中使用的用户是 nobody,否则会出现下面的permission denied之类的权限错误
  • PromQL其实就是 prometheus 便于数据聚合展示开发的一套 ad hoc 查询语言的,你想要查什么找对应函数取你的数据好了。
  •  
    "参数storage.tsdb.path指定了 TSDB 数据的存储路径、通过storage.tsdb.retention设置了保留多长时间的数据,还有下面的web.enable-admin-api参数可以用来开启对 admin api 的访问权限,参数web.enable-lifecycle非常重要,用来开启支持热更新的,有了这个参数之后,prometheus.yml 配置文件只要更新了,通过执行localhost:9090/-/reload就会立即生效,所以一定要加上这个参数。"
張 旭

HowTo/LDAP - FreeIPA - 0 views

  • The basedn in an IPA installation consists of a set of domain components (dc) for the initial domain that IPA was configured with.
  • You will only ever have one basedn, the one defined during installation.
  • find your basedn, and other interesting things, in /etc/ipa/default.conf
  • ...8 more annotations...
  • IPA uses a flat structure, storing like objects in what we call containers.
  • Users: cn=users,cn=accounts,$SUFFIX Groups: cn=groups,cn=accounts,$SUFFIX
  • Do not use the Directory Manager account to authenticate remote services to the IPA LDAP server. Use a system account
  • The reason to use an account like this rather than creating a normal user account in IPA and using that is that the system account exists only for binding to LDAP. It is not a real POSIX user, can't log into any systems and doesn't own any files.
  • This use also has no special rights and is unable to write any data in the IPA LDAP server, only read.
  • When possible, configure your LDAP client to communicate over SSL/TLS.
  • The IPA CA certificate can be found in /etc/ipa/ca.crt
  • /etc/openldap/ldap.conf
張 旭

APP_KEY And You | Tighten - 0 views

  • The application key is a random, 32-character string stored in the APP_KEY key in your .env file.
  • Once your app is running, there's one place it uses the APP_KEY: cookies.
  • Laravel uses the key for all encrypted cookies, including the session cookie, before handing them off to the user's browser, and it uses it to decrypt cookies read from the browser.
  • ...16 more annotations...
  • Encrypted cookies are an important security feature in Laravel.
  • All of this encryption and decryption is handled in Laravel by the Encrypter using PHP's built-in security tools, including OpenSSL.
  • Passwords are not encrypted, they are hashed.
  • Laravel's passwords are hashed using Hash::make() or bcrypt(), neither of which use APP_KEY.
  • Crypt (symmetric encryption) and Hash (one-way cryptographic hashing).
  • Laravel uses this same method for cookies, both the sender and receiver, using APP_KEY as the encryption key.
  • something like user passwords, you should never have a way to decrypt them. Ever.
  • Unique: The collision rate (different inputs hashing to the same output) should be very small
  • Laravel hashing implements the native PHP password_hash() function, defaulting to a hashing algorithm called bcrypt.
  • a one-way hash, we cannot decrypt it. All that we can do is test against it.
  • When the user with this password attempts to log in, Laravel hashes their password input and uses PHP’s password_verify() function to compare the new hash with the database hash
  • User password storage should never be reversible, and therefore doesn’t need APP_KEY at all.
  • Any good credential management strategy should include rotation: changing keys and passwords on a regular basis
  • update the key on each server.
  • their sessions invalidated as soon as you change your APP_KEY.
  • make and test a plan to decrypt that data with your old key and re-encrypt it with the new key.
張 旭

The Squeaky Blog | Why we don't use a staging environment - 0 views

  • Pre-live environments are never at parity with production
  • multiple people use staging to validate their changes before release.
  • Branches are then constantly out of sync with each other, and problems often surface when you merge, rebase, and backfill hotfixes.
  • ...10 more annotations...
  • Big Bang releases
  • there is a lengthy suite of tests and checks that run before it is deployed to staging. During this period, which could end up being hours, engineers will likely pick up another task. I’ve seen people merge, and then forget that their changes are on staging, more times than I can count.
  • only merge code that is ready to go live
  • written sufficient tests and have validated our changes in development.
  • All branches are cut from main, and all changes get merged back into main.
  • If we ever have an issue in production, we always roll forward.
  • Feature flags can be enabled on a per-user basis so we can monitor performance and gather feedback
  • Experimental features can be enabled by users in their account settings.
  • we have monitoring, logging, and alarms around all of our services. We also blue/green deploy, by draining and replacing a percentage of containers.
  • Dropping your staging environment in favour of true continuous integration and deployment can create a different mindset for shipping software.
  •  
    "Pre-live environments are never at parity with production "
張 旭

Considerations for large clusters | Kubernetes - 0 views

  • A cluster is a set of nodes (physical or virtual machines) running Kubernetes agents, managed by the control plane.
  • Kubernetes v1.23 supports clusters with up to 5000 nodes.
  • criteria: No more than 110 pods per node No more than 5000 nodes No more than 150000 total pods No more than 300000 total containers
  • ...14 more annotations...
  • In-use IP addresses
  • run one or two control plane instances per failure zone, scaling those instances vertically first and then scaling horizontally after reaching the point of falling returns to (vertical) scale.
  • Kubernetes nodes do not automatically steer traffic towards control-plane endpoints that are in the same failure zone
  • store Event objects in a separate dedicated etcd instance.
  • start and configure additional etcd instance
  • Kubernetes resource limits help to minimize the impact of memory leaks and other ways that pods and containers can impact on other components.
  • Addons' default limits are typically based on data collected from experience running each addon on small or medium Kubernetes clusters.
  • When running on large clusters, addons often consume more of some resources than their default limits.
  • Many addons scale horizontally - you add capacity by running more pods
  • The VerticalPodAutoscaler can run in recommender mode to provide suggested figures for requests and limits.
  • Some addons run as one copy per node, controlled by a DaemonSet: for example, a node-level log aggregator.
  • VerticalPodAutoscaler is a custom resource that you can deploy into your cluster to help you manage resource requests and limits for pods.
  • The cluster autoscaler integrates with a number of cloud providers to help you run the right number of nodes for the level of resource demand in your cluster.
  • The addon resizer helps you in resizing the addons automatically as your cluster's scale changes.
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