github.com/uber/kraken@v0.1.4/agent/agentclient/client.go (about)

     1  // Copyright (c) 2016-2019 Uber Technologies, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  package agentclient
    15  
    16  import (
    17  	"errors"
    18  	"fmt"
    19  	"io"
    20  	"io/ioutil"
    21  	"net/url"
    22  
    23  	"github.com/uber/kraken/core"
    24  	"github.com/uber/kraken/utils/httputil"
    25  )
    26  
    27  // Client errors.
    28  var (
    29  	ErrTagNotFound = errors.New("tag not found")
    30  )
    31  
    32  // Client defines a client for accessing the agent server.
    33  type Client interface {
    34  	GetTag(tag string) (core.Digest, error)
    35  	Download(namespace string, d core.Digest) (io.ReadCloser, error)
    36  }
    37  
    38  // HTTPClient provides a wrapper for HTTP operations on an agent.
    39  type HTTPClient struct {
    40  	addr string
    41  }
    42  
    43  // New creates a new client for an agent at addr.
    44  func New(addr string) *HTTPClient {
    45  	return &HTTPClient{addr}
    46  }
    47  
    48  // GetTag resolves tag into a digest. Returns ErrTagNotFound if the tag does
    49  // not exist.
    50  func (c *HTTPClient) GetTag(tag string) (core.Digest, error) {
    51  	resp, err := httputil.Get(fmt.Sprintf("http://%s/tags/%s", c.addr, url.PathEscape(tag)))
    52  	if err != nil {
    53  		if httputil.IsNotFound(err) {
    54  			return core.Digest{}, ErrTagNotFound
    55  		}
    56  		return core.Digest{}, err
    57  	}
    58  	defer resp.Body.Close()
    59  	b, err := ioutil.ReadAll(resp.Body)
    60  	if err != nil {
    61  		return core.Digest{}, fmt.Errorf("read body: %s", err)
    62  	}
    63  	d, err := core.ParseSHA256Digest(string(b))
    64  	if err != nil {
    65  		return core.Digest{}, fmt.Errorf("parse digest: %s", err)
    66  	}
    67  	return d, nil
    68  }
    69  
    70  // Download returns the blob of d. Callers should close the returned ReadCloser
    71  // when done reading the blob.
    72  func (c *HTTPClient) Download(namespace string, d core.Digest) (io.ReadCloser, error) {
    73  	resp, err := httputil.Get(
    74  		fmt.Sprintf(
    75  			"http://%s/namespace/%s/blobs/%s",
    76  			c.addr, url.PathEscape(namespace), d))
    77  	if err != nil {
    78  		return nil, err
    79  	}
    80  	return resp.Body, nil
    81  }