Coder uses image tags to determine the image variant to use when creating an environment.
Image tags are expressed using the following notation:
ubuntu:rolling ubuntu:latest ubuntu:20.04 mycorp/myproject:v1
This article will walk you through how Coder handles image tags and what to consider when working with image tags.
When modifying an existing image, be sure to consider whether the changes you're making will break existing environments built using that image. You may want to consider taking a semantic versioning view of your image tags for more critical images.
The following examples show how different tagging schemes change how Coder uses the image tag.
If you build your environment using a
Coder prompts you to rebuild for patches, security updates, and major version
releases. If you're supporting a SaaS product or working on mobile apps, you
may opt for this to ensure that your tools stay up-to-date.
If you build your environment using a specific version tag (e.g.,
ubuntu:20.04), Coder will alert you regarding patches and security updates
so that you rebuild your environment (you won't get these fixes otherwise).
Coder does not, however, alert you regarding minor releases (e.g., movement
20.10). This is a good option for those offering long-term
support of software with lengthier version cycles or those supporting multiple
versions where you expect to revert to a prior release to investigate and fix
If you build your environment using
mycorp/myproject:v1, the image is
associated with a specific project's major version. You can apply the
tag to the most recent build for the image, while you can use
:v1.3.1 to pull a more specific tag version.
Use image names and tags that follow a consistent format across the organization so that users will be comfortable selecting either a versioned or a rolling tag.
To avoid pulling images from Docker Hub (or another external source), use internal registry names and tags or namespaces that are controlled by your organization.
Let's say that you have the following tag:
Here's the information that can be gleaned from the tag name:
registry:port: By using an internal image registry name, there's no risk of pulling an outside image with unapproved content
company: If you're using an internal registry, you can omit this parameter
department: Helps set the scope for who owns the image and therefore can patch/modify the image
software: Offers information about which software systems should be developed using the image
majorversion: Can correlate to a software stock; helpful in determining which version of various dependencies and build tools are present in the image
The above recommendations are based on assumptions that may not apply to all organizations, and their applicability may change over time. There's no "right way" to tag your images, as long as your tags are meaningful to your teams and don't cause issues with your developers' workflows.