Identifiers
A Docker Container can be identified in three ways: long form UUID (Universally Unique Identifier), a short form UUID and by Name. Identifiers help prevent naming conflicts and facilitate automation. |
- UUID
- Universally Unique Identifier
- Assigned to a container on creation.
- UUIDs come in two forms:
- a 64 character long form, e.g.
- “f78375b1c487e03c9438c729345e54db9d20cfa2ac1fc3494b6eb60872e74778”
- an abbreviated 12 character short form, e.g.
- “f78375b1c487”
- automatically generated and applied by the Docker daemon
- Identifiers are commonly displayed in a truncated 12-character form
- Name
- A container name is generated and automatically assigned
- Generated name format: <adjective>_<notable names>
- On the left a list of strings, approximately 90 adjectives
- On the right a list of approximately 150 "notable" scientists and hackers
- Manually assign a container name using the --name option
- Images can be further identified using: image:[tag] and image@[digest]
- Image:[tag]
- :tag allows you to add a version to an image, e.g. ubuntu:16.04, where ubuntu is the image, 16.04 is the tag (or version)
- Image:[@digest]
- A content addressable identifier, e.g. sha256:58e1a1bb75db1b5a24a462dd5e2915277ea06438c3f105138f97eb53149673c4
- As long as the makeup of the image is the same, it's DIGEST value is a predictable and referenceable value, i.e. two images with the same DIGEST value can be assumed to be the same image
- docker images --digests to display the DIGEST value of an image
- An image can be pulled using the DIGEST value
- Images and containers may be identified in one of three ways:
Identifier Type | Example Value | Length |
UUID long identifier | f78375b1c887e03c9438c729345e54db9d20cfa2ac1fc3494b6eb60872e74778 | 64-character |
UUID short identifier | f78375b1c887 | 12-character |
Name | Pseudo-random generated names | Variable |
Tag | String identifying a version of an image | Variable |
Digest | Calculated SHA value of an image | 64-character |
References:
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