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1# This file is part of daf_butler. 

2# 

3# Developed for the LSST Data Management System. 

4# This product includes software developed by the LSST Project 

5# (http://www.lsst.org). 

6# See the COPYRIGHT file at the top-level directory of this distribution 

7# for details of code ownership. 

8# 

9# This program is free software: you can redistribute it and/or modify 

10# it under the terms of the GNU General Public License as published by 

11# the Free Software Foundation, either version 3 of the License, or 

12# (at your option) any later version. 

13# 

14# This program is distributed in the hope that it will be useful, 

15# but WITHOUT ANY WARRANTY; without even the implied warranty of 

16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

17# GNU General Public License for more details. 

18# 

19# You should have received a copy of the GNU General Public License 

20# along with this program. If not, see <http://www.gnu.org/licenses/>. 

21 

22from __future__ import annotations 

23 

24__all__ = ("getS3Client", "s3CheckFileExists", "bucketExists", "setAwsEnvCredentials", 

25 "unsetAwsEnvCredentials") 

26 

27import os 

28 

29from typing import ( 

30 Optional, 

31 Tuple, 

32 Union, 

33) 

34 

35try: 

36 import boto3 

37except ImportError: 

38 boto3 = None 

39 

40try: 

41 import botocore 

42except ImportError: 

43 botocore = None 

44 

45from .location import Location 

46from ._butlerUri import ButlerURI 

47 

48 

49def getS3Client() -> boto3.client: 

50 """Create a S3 client with AWS (default) or the specified endpoint 

51 

52 Returns 

53 ------- 

54 s3client : `botocore.client.S3` 

55 A client of the S3 service. 

56 

57 Notes 

58 ----- 

59 The endpoint URL is from the environment variable S3_ENDPOINT_URL. 

60 If none is specified, the default AWS one is used. 

61 """ 

62 if boto3 is None: 

63 raise ModuleNotFoundError("Could not find boto3. " 

64 "Are you sure it is installed?") 

65 if botocore is None: 

66 raise ModuleNotFoundError("Could not find botocore. " 

67 "Are you sure it is installed?") 

68 

69 endpoint = os.environ.get("S3_ENDPOINT_URL", None) 

70 if not endpoint: 

71 endpoint = None # Handle "" 

72 

73 config = botocore.config.Config( 

74 read_timeout=180, 

75 retries={ 

76 'mode': 'adaptive', 

77 'max_attempts': 10 

78 } 

79 ) 

80 

81 return boto3.client("s3", endpoint_url=endpoint, config=config) 

82 

83 

84def s3CheckFileExists(path: Union[Location, ButlerURI, str], bucket: Optional[str] = None, 

85 client: Optional[boto3.client] = None) -> Tuple[bool, int]: 

86 """Returns (True, filesize) if file exists in the bucket and (False, -1) if 

87 the file is not found. 

88 

89 Parameters 

90 ---------- 

91 path : `Location`, `ButlerURI` or `str` 

92 Location or ButlerURI containing the bucket name and filepath. 

93 bucket : `str`, optional 

94 Name of the bucket in which to look. If provided, path will be assumed 

95 to correspond to be relative to the given bucket. 

96 client : `boto3.client`, optional 

97 S3 Client object to query, if not supplied boto3 will try to resolve 

98 the credentials as in order described in its manual_. 

99 

100 Returns 

101 ------- 

102 exists : `bool` 

103 True if key exists, False otherwise. 

104 size : `int` 

105 Size of the key, if key exists, in bytes, otherwise -1 

106 

107 Notes 

108 ----- 

109 S3 Paths are sensitive to leading and trailing path separators. 

110 

111 .. _manual: https://boto3.amazonaws.com/v1/documentation/api/latest/guide/\ 

112 configuration.html#configuring-credentials 

113 """ 

114 if boto3 is None: 

115 raise ModuleNotFoundError("Could not find boto3. " 

116 "Are you sure it is installed?") 

117 

118 if client is None: 

119 client = getS3Client() 

120 

121 if isinstance(path, str): 

122 if bucket is not None: 

123 filepath = path 

124 else: 

125 uri = ButlerURI(path) 

126 bucket = uri.netloc 

127 filepath = uri.relativeToPathRoot 

128 elif isinstance(path, (ButlerURI, Location)): 

129 bucket = path.netloc 

130 filepath = path.relativeToPathRoot 

131 

132 try: 

133 obj = client.head_object(Bucket=bucket, Key=filepath) 

134 return (True, obj["ContentLength"]) 

135 except client.exceptions.ClientError as err: 

136 # resource unreachable error means key does not exist 

137 if err.response["ResponseMetadata"]["HTTPStatusCode"] == 404: 

138 return (False, -1) 

139 # head_object returns 404 when object does not exist only when user has 

140 # s3:ListBucket permission. If list permission does not exist a 403 is 

141 # returned. In practical terms this generally means that the file does 

142 # not exist, but it could also mean user lacks s3:GetObject permission: 

143 # https://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectHEAD.html 

144 # I don't think its possible to discern which case is it with certainty 

145 if err.response["ResponseMetadata"]["HTTPStatusCode"] == 403: 

146 raise PermissionError("Forbidden HEAD operation error occured. " 

147 "Verify s3:ListBucket and s3:GetObject " 

148 "permissions are granted for your IAM user. ") from err 

149 raise 

150 

151 

152def bucketExists(bucketName: str, client: Optional[boto3.client] = None) -> bool: 

153 """Check if the S3 bucket with the given name actually exists. 

154 

155 Parameters 

156 ---------- 

157 bucketName : `str` 

158 Name of the S3 Bucket 

159 client : `boto3.client`, optional 

160 S3 Client object to query, if not supplied boto3 will try to resolve 

161 the credentials as in order described in its manual_. 

162 

163 Returns 

164 ------- 

165 exists : `bool` 

166 True if it exists, False if no Bucket with specified parameters is 

167 found. 

168 

169 .. _manual: https://boto3.amazonaws.com/v1/documentation/api/latest/guide/\ 

170 configuration.html#configuring-credentials 

171 """ 

172 if boto3 is None: 

173 raise ModuleNotFoundError("Could not find boto3. " 

174 "Are you sure it is installed?") 

175 

176 if client is None: 

177 client = getS3Client() 

178 try: 

179 client.get_bucket_location(Bucket=bucketName) 

180 return True 

181 except client.exceptions.NoSuchBucket: 

182 return False 

183 

184 

185def setAwsEnvCredentials(accessKeyId: str = 'dummyAccessKeyId', 

186 secretAccessKey: str = "dummySecretAccessKey") -> bool: 

187 """Set AWS credentials environmental variables AWS_ACCESS_KEY_ID and 

188 AWS_SECRET_ACCESS_KEY. 

189 

190 Parameters 

191 ---------- 

192 accessKeyId : `str` 

193 Value given to AWS_ACCESS_KEY_ID environmental variable. Defaults to 

194 'dummyAccessKeyId' 

195 secretAccessKey : `str` 

196 Value given to AWS_SECRET_ACCESS_KEY environmental variable. Defaults 

197 to 'dummySecretAccessKey' 

198 

199 Returns 

200 ------- 

201 setEnvCredentials : `bool` 

202 True when environmental variables were set, False otherwise. 

203 

204 Notes 

205 ----- 

206 If either AWS_ACCESS_KEY_ID or AWS_SECRET_ACCESS_KEY are not set, both 

207 values are overwritten. 

208 """ 

209 if "AWS_ACCESS_KEY_ID" not in os.environ or "AWS_SECRET_ACCESS_KEY" not in os.environ: 

210 os.environ["AWS_ACCESS_KEY_ID"] = accessKeyId 

211 os.environ["AWS_SECRET_ACCESS_KEY"] = secretAccessKey 

212 return True 

213 return False 

214 

215 

216def unsetAwsEnvCredentials() -> None: 

217 """Unsets AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environmental 

218 variables. 

219 """ 

220 if "AWS_ACCESS_KEY_ID" in os.environ: 

221 del os.environ["AWS_ACCESS_KEY_ID"] 

222 if "AWS_SECRET_ACCESS_KEY" in os.environ: 

223 del os.environ["AWS_SECRET_ACCESS_KEY"]