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Snapshotting Worflow

Snapshotting is a technique provided by tc to capture the Topology definition along with all the sub versions of its nodes and entities. It is not to be confused with a manifest of versions. We can freeze a sandbox, snapshot it, store the snapshot in S3 or filesystem and render the snapshot of a Topology in any sandbox and profile.

Snapshotting is not to be confused with capturing only the topology versions of the system. Following is the structure of a snapshot:

[{
    "changed": true,
    "changelog": ["PR-1123 ..."],
    "dir": "./path/to/topology",
    "git_version": "",
    "kind": "routed",
    "namespace": "topo-1",
    "prev_version": "",
    "sandbox": "stable",
    "tc_version": "",
    "updated_at": "",
    "updated_by": "",
    "version": "0.1.1",
    "topology": Topology
}]

  1. Freeze

    Terminal window
    tc freeze -s stable -e qa

    Freeze is a software-enforced freeze. Test! Test! Test! after freeze.

  2. Snapshot

    Terminal window
    tc snapshot -s stable -e qa --save

    This saves the snapshot of manifests, changelog and topology definitions to s3.

  3. Unfreeze

    Terminal window
    tc unfreeze -s stable -e qa

    This allows Continuous deploys to continue.

  4. Promote

    To promote a snapshot, we first go back and pick the one that has been certified and tested in QA. For example:

    Terminal window
    tc snapshot --list
    qa/stable/2025-10-02
    qa/stable/2025-10-01
    qa/stable/2025-09-30
    qa/stable/2025-09-29
    qa/stable/2025-09-18

    To deploy a snapshot (say qa/stable/2025-10-02), we do:

    Terminal window
     tc ci-deploy --env prod --sandbox stable --snapshot qa/stable/2025-10-02

    Behind the scenes, ci-deploy triggers a pipeline using the snapshot:

    Terminal window
    tc snapshot --show qa/stable/2025-10-02 -f pipeline --target-env dev --target-sandbox stable