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WIP: translate: Stub in a translation framework
Add tooling to translate higher-level configs into the basic OCI
config. On IRC, Julz floated a linux.namespaces[].fromContainer as a
higher-level version of linux.namespaces[].path for emulating exec
[1]. That makes sense to me, and Mrunal is open to something like
[2]:
$ ocitools generate --template=high-level-config.json --translate=fromContainer --runtime=runc
The interface{} -> rspec.Spec conversion happens through a JSON
serialization trick suggested by 梁辰晔 (Liang Chenye) [3] after the
translations, because before the translations the template may contain
JSON that's not represented in the OCI Spec structure
(e.g. fromContainer in namespace entries).
This commit still needs (marked by FIXMEs):
* Lookup /proc in /proc/self/mounts (recursive?).
* Compare /proc with state JSON namespace [4].
* A way to handle nested definition lists in man pages. I expect we
should drop go-md2man in favor of a more established man-page format
(e.g. AsciiDoc).
[1]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-04-27.log.html#t2016-04-27T20:32:09
[2]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-04-28.log.html#t2016-04-28T16:12:48
[3]: #54 (comment)
[4]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/ujtABQoCmgk
Subject: Linux: Adding the PID namespace inode to state JSON
Date: Wed, 30 Dec 2015 21:34:57 -0800
Message-ID: <[email protected]>
Signed-off-by: W. Trevor King <[email protected]>- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,95 @@ | ||
| package translate | ||
|
|
||
| import ( | ||
| "bytes" | ||
| "encoding/json" | ||
| "fmt" | ||
| "os/exec" | ||
| "path/filepath" | ||
|
|
||
| "github.com/codegangsta/cli" | ||
| rspec "github.com/opencontainers/runtime-spec/specs-go" | ||
| ) | ||
|
|
||
| func FromContainer(data interface{}, context *cli.Context) (translated interface{}, err error) { | ||
| dataMap, ok := data.(map[string]interface{}) | ||
| if !ok { | ||
| return nil, fmt.Errorf("data is not a map[string]interface{}: %s", data) | ||
| } | ||
|
|
||
| linuxInterface, ok := dataMap["linux"] | ||
| if !ok { | ||
| return data, nil | ||
| } | ||
|
|
||
| linux, ok := linuxInterface.(map[string]interface{}) | ||
| if !ok { | ||
| return nil, fmt.Errorf("data.linux is not a map[string]interface{}: %s", linuxInterface) | ||
| } | ||
|
|
||
| namespacesInterface, ok := linux["namespaces"] | ||
| if !ok { | ||
| return data, nil | ||
| } | ||
|
|
||
| namespaces, ok := namespacesInterface.([]interface{}) | ||
| if !ok { | ||
| return nil, fmt.Errorf("data.linux.namespaces is not an array: %s", namespacesInterface) | ||
| } | ||
|
|
||
| for index, namespaceInterface := range namespaces { | ||
| namespace, ok := namespaceInterface.(map[string]interface{}) | ||
| if !ok { | ||
| return nil, fmt.Errorf("data.linux.namespaces[%d] is not a map[string]interface{}: %s", index, namespaceInterface) | ||
| } | ||
| err := namespaceFromContainer(&namespace, index, context) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| } | ||
|
|
||
| return data, nil | ||
| } | ||
|
|
||
| func namespaceFromContainer(namespace *map[string]interface{}, index int, context *cli.Context) (err error) { | ||
| fromContainerInterface, ok := (*namespace)["fromContainer"] | ||
| if ok { | ||
| fromContainer, ok := fromContainerInterface.(string) | ||
| if !ok { | ||
| return fmt.Errorf("data.linux.namespaces[%d].fromContainer is not a string: %s", index, fromContainerInterface) | ||
| } | ||
| delete(*namespace, "fromContainer") | ||
| runtime := context.String("runtime") | ||
| if (len(runtime) == 0) { | ||
| return fmt.Errorf("translating fromContainer requires a non-empty --runtime") | ||
| } | ||
| command := exec.Command(runtime, "state", fromContainer) | ||
| var out bytes.Buffer | ||
| command.Stdout = &out | ||
| err := command.Run() | ||
| if err != nil { | ||
| return err | ||
| } | ||
| var state rspec.State | ||
| err = json.Unmarshal(out.Bytes(), &state) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| namespaceTypeInterface, ok := (*namespace)["type"] | ||
| if !ok { | ||
| return fmt.Errorf("data.linux.namespaces[%d].type is missing: %s", index, fromContainerInterface) | ||
| } | ||
| namespaceType, ok := namespaceTypeInterface.(string) | ||
| if !ok { | ||
| return fmt.Errorf("data.linux.namespaces[%d].type is not a string: %s", index, namespaceTypeInterface) | ||
| } | ||
| switch namespaceType { | ||
| case "network": namespaceType = "net" | ||
| case "mount": namespaceType = "mnt" | ||
| } | ||
| proc := "/proc" // FIXME: lookup in /proc/self/mounts, check right namespace | ||
| path := filepath.Join(proc, fmt.Sprint(state.Pid), "ns", namespaceType) | ||
| (*namespace)["path"] = path | ||
| } | ||
| return nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,20 @@ | ||
| /* | ||
| Package translate handles translation between configuration | ||
| specifications. | ||
| For example, it allows you to generate OCI-compliant config.json from | ||
| a higher-level configuration language. | ||
| */ | ||
| package translate | ||
|
|
||
| import ( | ||
| "github.com/codegangsta/cli" | ||
| ) | ||
|
|
||
| // Translate maps JSON from one specification to another. | ||
| type Translate func(data interface{}, context *cli.Context) (translated interface{}, err error) | ||
|
|
||
| // Translators is a map from translator names to Translate functions. | ||
| var Translators = map[string]Translate{ | ||
| "fromContainer": FromContainer, | ||
| } |