Builtin Helm client and Tiller
In the werf tiller is built into main werf deploy process. Thus it runs in the user space without need to connect to tiller server.
Yet werf is fully compatible with already existing helm 2 installations.
This architecture gives werf following advantages.
Ability to implement resources tracking properly
Werf imports helm codebase and redefines key points of helm standard deploy process. These changes making it possible to track resources with logs without complex architectural solutions such as streaming of logs over grpc when using helm client with tiller server.
Typically Tiller is deployed into cluster with admin permissions. With werf user can setup fine grained access to cluster for example per project namespace.
In contrast to Tiller, releases storage in Werf is not a static configuration of cluster installation. Thus Werf can store releases of each project right in the namespace of the project, so that neighbour projects does not have ability to see other releases if there is no access to these neighbour namespaces.
As helm client and tiller is built into werf there is no need for helm client installed on the host nor tiller installed in the cluster.
Proper tracking of deployed resources
Werf tracks all chart resources until each resource reaches ready state and prints logs and info about current resources status, resources status changes during deploy process and “what werf is waiting for?”.
With pure helm user has only the ability to wait for resources using
--wait flag, but helm does not provide any interactive info about “what is going on now?” when using this flag.
Also werf fails fast when there is an error occurred during deploy process. With pure helm and wait flag user should wait till timeout occurred when something went wrong. And failed deploys is not a rare case, so waiting for timeouts significantly slows down CI/CD experience.
And additionally default tracking and error response behaviour can be configured, see deploy essentials for more info.
Werf uses kubedog resource tracking library under the hood.
Annotate and label chart resources
Werf automatically appends annotations to all chart resources (including hooks), such as (for GitLab):
User can pass any additional annotations and labels to werf deploy invocation and werf will set these annotations to all resources of the chart.
This feature opens possibilities for grouping resources by project name, url, etc. for example in monitoring task.
Helm does not have this ability yet and will not have in the near future, see issue.
Parallel deploys are safe
Werf uses locks system to prevent any parallel deploys or dismisses when working with a single release. Release is locked by name.
Helm does not use any locks, so parallel deploys may lead to unexpected results.
Builtin secrets support
Integration with built images
Werf extends helm with special templates functions such as
werf_container_env to generate images names for the images built with werf builder. See deploy essentials for more info.
Thus werf makes it super easy for the user to integrate custom built images into user templates: werf does the work of generating “the right” docker images names and tags, and werf makes sure that image will be pulled when it is necessary for kubernetes to pull new image version.
Using pure helm user need to invent own system of passing actual images names using values.
During werf deploy a temporary helm chart is created.
This chart contains:
- Additional generated go-templates:
werf_container_envand other. These templates are described in the templates article.
- Decoded secret values yaml file. The secrets are described in the secrets article.
The temporary chart then goes to the helm subsystem inside werf. Werf deletes this chart on the werf deploy command termination.
Chart.yaml is not required
Helm chart requires
Chart.yaml file in the root of the chart which should define chart name and version.
Werf internally generates this file when passing temporal chart to the builtin helm subsystem. In this generated file chart name equals project name from
werf.yaml config and version is always
0.1.0 (version is an unimportant auxiliary field).
If user have created
Chart.yaml by itself, then werf will overwrite it in the generated actual chart and print a warning.
Fixed helm chart path in the project
Werf requires chart to be placed in the
.helm directory in the same directory where
werf.yaml config is placed.
Helm does not define a static place in the project where helm chart should be stored.
Chart resource validation
Errors like non-existing fields in resource configuration of chart templates are not shown by standard helm. No feedback is given to the user.
Werf writes all validation errors as WARNINGS and also writes these warnings into the resource annotation (so that all these warnings can easily be fetched by cli scripts from multiple clusters). See more into in the article.
Three way merge
Werf is now in the process of migrating to three-way-merge based resources updates. See more into in the article.