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6e967780c9
Closes https://github.com/coder/internal/issues/369 We can't know whether a replacement (i.e. drift of terraform state leading to a resource needing to be deleted/recreated) will take place apriori; we can only detect it at `plan` time, because the provider decides whether a resource must be replaced and it cannot be inferred through static analysis of the template. **This is likely to be the most common gotcha with using prebuilds, since it requires a slight template modification to use prebuilds effectively**, so let's head this off before it's an issue for customers. Drift details will now be logged in the workspace build logs:  Plus a notification will be sent to template admins when this situation arises:  A new metric - `coderd_prebuilt_workspaces_resource_replacements_total` - will also increment each time a workspace encounters replacements. We only track _that_ a resource replacement occurred, not how many. Just one is enough to ruin a prebuild, but we can't know apriori which replacement would cause this. For example, say we have 2 replacements: a `docker_container` and a `null_resource`; we don't know which one might cause an issue (or indeed if either would), so we just track the replacement. --------- Signed-off-by: Danny Kopping <dannykopping@gmail.com>
87 lines
2.7 KiB
Go
87 lines
2.7 KiB
Go
package terraform
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import (
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"fmt"
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"strings"
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tfjson "github.com/hashicorp/terraform-json"
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)
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type resourceReplacements map[string][]string
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// resourceReplacements finds all resources which would be replaced by the current plan, and the attribute paths which
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// caused the replacement.
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//
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// NOTE: "replacement" in terraform terms means that a resource will have to be destroyed and replaced with a new resource
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// since one of its immutable attributes was modified, which cannot be updated in-place.
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func findResourceReplacements(plan *tfjson.Plan) resourceReplacements {
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if plan == nil {
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return nil
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}
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// No changes, no problem!
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if len(plan.ResourceChanges) == 0 {
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return nil
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}
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replacements := make(resourceReplacements, len(plan.ResourceChanges))
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for _, ch := range plan.ResourceChanges {
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// No change, no problem!
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if ch.Change == nil {
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continue
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}
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// No-op change, no problem!
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if ch.Change.Actions.NoOp() {
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continue
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}
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// No replacements, no problem!
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if len(ch.Change.ReplacePaths) == 0 {
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continue
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}
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// Replacing our resources: could be a problem - but we ignore since they're "virtual" resources. If any of these
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// resources' attributes are referenced by non-coder resources, those will show up as transitive changes there.
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// i.e. if the coder_agent.id attribute is used in docker_container.env
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//
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// Replacing our resources is not strictly a problem in and of itself.
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//
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// NOTE:
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// We may need to special-case coder_agent in the future. Currently, coder_agent is replaced on every build
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// because it only supports Create but not Update: https://github.com/coder/terraform-provider-coder/blob/5648efb/provider/agent.go#L28
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// When we can modify an agent's attributes, some of which may be immutable (like "arch") and some may not (like "env"),
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// then we'll have to handle this specifically.
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// This will only become relevant once we support multiple agents: https://github.com/coder/coder/issues/17388
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if strings.Index(ch.Type, "coder_") == 0 {
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continue
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}
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// Replacements found, problem!
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for _, val := range ch.Change.ReplacePaths {
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var pathStr string
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// Each path needs to be coerced into a string. All types except []interface{} can be coerced using fmt.Sprintf.
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switch path := val.(type) {
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case []interface{}:
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// Found a slice of paths; coerce to string and join by ".".
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segments := make([]string, 0, len(path))
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for _, seg := range path {
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segments = append(segments, fmt.Sprintf("%v", seg))
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}
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pathStr = strings.Join(segments, ".")
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default:
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pathStr = fmt.Sprintf("%v", path)
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}
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replacements[ch.Address] = append(replacements[ch.Address], pathStr)
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}
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}
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if len(replacements) == 0 {
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return nil
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}
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return replacements
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}
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