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72c91e378d
Looking in history to learn why this struct existed, shows that this type was mostly the result of tech-debt accumulating over time; - originally ([moby@1aa7f13]) most of the request handling was internal; the [`call()` function][1] would make a request, read the `response.Body`, and return it as a `[]byte` (or an error if one happened). - some features needed the statuscode, so [moby@a4bcf7e] added an extra output variable to return the `response.StatusCode`. - some new features required streaming, so [moby@fdd8d4b] changed the function to return the `response.Body` as a `io.ReadCloser`, instead of a `[]byte`. - some features needed access to the content-type header, so a new `clientRequest` method was introduced in [moby@6b2eeaf] to read the `Content-Type` header from `response.Headers` and return it as a string. - of course, `Content-Type` may not be the only header needed, so [moby@0cdc3b7] changed the signature to return `response.Headers` as a whole as a `http.Header` - things became a bit unwieldy now, with the function having four (4) output variables, so [moby@126529c] chose to refactor this code, introducing a `serverResponse` struct to wrap them all, not realizing that all these values were effectively deconstructed from the `url.Response`, so now re-assembling them into our own "URL response", only preserving a subset of the information available. - now that we had a custom struct, it was possible to add more information to it without changing the signature. When there was a need to know the URL of the request that initiated the response, [moby@27ef09a] introduced a `reqURL` field to hold the `request.URL` which notably also is available in `response.Request.URL`. In short; - The original implementation tried to (pre-maturely) abstract the underlying response to provide a simplified interface. - While initially not needed, abstracting caused relevant information from the response (and request) to be unavailable to callers. - As a result, we ended up in a situation where we are deconstructing the original `url.Response`, only to re-assemble it into our own, custom struct (`serverResponsee`) with only a subset of the information preserved. This patch removes the `serverResponse` struct, instead returning the `url.Response` as-is, so that all information is preserved, allowing callers to use the information they need. There is one follow-up change to consider; commit [moby@589df17] introduced a `ensureReaderClosed` utility. Before that commit, the response body would be closed in a more idiomatic way through a [`defer serverResp.body.Close()`][2]. A later change in [docker/engine-api@5dd6452] added an optimization to that utility, draining the response to allow connections to be reused. While skipping that utility (and not draining the response) would not be a critical issue, it may be easy to overlook that utility, and to close the response body in the "idiomatic" way, resulting in a possible performance regression. We need to check if that optimization is still relevant or if later changes in Go itself already take care of this; we should also look if context cancellation is handled correctly for these. If it's still relevant, we could - Wrap the the `url.Response` in a custom struct ("drainCloser") to provide a `Close()` function handling the draining and closing; this would re- introduce a custom type to be returned, so perhaps not what we want. - Wrap the `url.Response.Body` in the response returned (so, calling) `response.Body.Close()` would call the wrapped closer. - Change the signature of `Client.sendRequest()` (and related) to return a `close()` func to handle this; doing so would more strongly encourage callers to close the response body. [1]:1aa7f1392d/commands.go (L1008-L1027)[2]:589df17a1a/api/client/ps.go (L84-L89)[moby@1aa7f13]:1aa7f1392d[moby@a4bcf7e]:a4bcf7e1ac[moby@fdd8d4b]:fdd8d4b7d9[moby@6b2eeaf]:6b2eeaf896[moby@0cdc3b7]:0cdc3b7539[moby@126529c]:126529c6d0[moby@27ef09a]:27ef09a46f[moby@589df17]:589df17a1a[docker/engine-api@5dd6452]:5dd6452d4dSigned-off-by: Sebastiaan van Stijn <github@gone.nl>
91 lines
3.0 KiB
Go
91 lines
3.0 KiB
Go
package client // import "github.com/docker/docker/client"
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import (
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"context"
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"encoding/json"
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"net/http"
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"net/url"
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"github.com/docker/docker/api/types"
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"github.com/docker/docker/api/types/registry"
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"github.com/docker/docker/api/types/swarm"
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"github.com/docker/docker/api/types/versions"
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)
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// ServiceUpdate updates a Service. The version number is required to avoid conflicting writes.
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// It should be the value as set *before* the update. You can find this value in the Meta field
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// of swarm.Service, which can be found using ServiceInspectWithRaw.
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func (cli *Client) ServiceUpdate(ctx context.Context, serviceID string, version swarm.Version, service swarm.ServiceSpec, options types.ServiceUpdateOptions) (swarm.ServiceUpdateResponse, error) {
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serviceID, err := trimID("service", serviceID)
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if err != nil {
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return swarm.ServiceUpdateResponse{}, err
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}
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// Make sure we negotiated (if the client is configured to do so),
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// as code below contains API-version specific handling of options.
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//
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// Normally, version-negotiation (if enabled) would not happen until
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// the API request is made.
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if err := cli.checkVersion(ctx); err != nil {
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return swarm.ServiceUpdateResponse{}, err
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}
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query := url.Values{}
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if options.RegistryAuthFrom != "" {
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query.Set("registryAuthFrom", options.RegistryAuthFrom)
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}
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if options.Rollback != "" {
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query.Set("rollback", options.Rollback)
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}
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query.Set("version", version.String())
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if err := validateServiceSpec(service); err != nil {
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return swarm.ServiceUpdateResponse{}, err
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}
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// ensure that the image is tagged
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var resolveWarning string
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switch {
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case service.TaskTemplate.ContainerSpec != nil:
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if taggedImg := imageWithTagString(service.TaskTemplate.ContainerSpec.Image); taggedImg != "" {
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service.TaskTemplate.ContainerSpec.Image = taggedImg
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}
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if options.QueryRegistry {
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resolveWarning = resolveContainerSpecImage(ctx, cli, &service.TaskTemplate, options.EncodedRegistryAuth)
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}
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case service.TaskTemplate.PluginSpec != nil:
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if taggedImg := imageWithTagString(service.TaskTemplate.PluginSpec.Remote); taggedImg != "" {
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service.TaskTemplate.PluginSpec.Remote = taggedImg
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}
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if options.QueryRegistry {
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resolveWarning = resolvePluginSpecRemote(ctx, cli, &service.TaskTemplate, options.EncodedRegistryAuth)
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}
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}
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headers := http.Header{}
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if versions.LessThan(cli.version, "1.30") {
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// the custom "version" header was used by engine API before 20.10
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// (API 1.30) to switch between client- and server-side lookup of
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// image digests.
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headers["version"] = []string{cli.version}
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}
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if options.EncodedRegistryAuth != "" {
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headers[registry.AuthHeader] = []string{options.EncodedRegistryAuth}
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}
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resp, err := cli.post(ctx, "/services/"+serviceID+"/update", query, service, headers)
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defer ensureReaderClosed(resp)
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if err != nil {
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return swarm.ServiceUpdateResponse{}, err
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}
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var response swarm.ServiceUpdateResponse
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err = json.NewDecoder(resp.Body).Decode(&response)
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if resolveWarning != "" {
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response.Warnings = append(response.Warnings, resolveWarning)
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}
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return response, err
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}
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