GIT_TRACE=1 以外にも色々な環境変数が指定できる。
HTTP 通信のログを見るには GIT_CURL_VERBOSE=1 を指定する。
debugging - How can I debug git/git-shell related problems? - Stack Overflow
GIT_CURL_VERBOSE=1 GIT_TRACE=1 git clone https://github.com/kyanny/hello
macOS 11.5.2 上の git 2.32.0 では以下のような出力になる。
$ GIT_CURL_VERBOSE=1 GIT_TRACE=1 git clone https://github.com/kyanny/hello 20:37:11.800261 git.c:455 trace: built-in: git clone https://github.com/kyanny/hello Cloning into 'hello'... 20:37:11.811327 run-command.c:667 trace: run_command: git remote-https origin https://github.com/kyanny/hello 20:37:11.816890 git.c:743 trace: exec: git-remote-https origin https://github.com/kyanny/hello 20:37:11.817559 run-command.c:667 trace: run_command: git-remote-https origin https://github.com/kyanny/hello 20:37:11.827675 http.c:756 == Info: Couldn't find host github.com in the .netrc file; using defaults 20:37:11.883106 http.c:756 == Info: Trying 13.114.40.48... 20:37:11.883150 http.c:756 == Info: TCP_NODELAY set 20:37:11.892599 http.c:756 == Info: Connected to github.com (13.114.40.48) port 443 (#0) 20:37:11.892742 http.c:756 == Info: ALPN, offering h2 20:37:11.892768 http.c:756 == Info: ALPN, offering http/1.1 20:37:11.898710 http.c:756 == Info: successfully set certificate verify locations: 20:37:11.898733 http.c:756 == Info: CAfile: /etc/ssl/cert.pem CApath: none 20:37:11.898843 http.c:756 == Info: TLSv1.2 (OUT), TLS handshake, Client hello (1): 20:37:11.907147 http.c:756 == Info: TLSv1.2 (IN), TLS handshake, Server hello (2): 20:37:11.907232 http.c:756 == Info: TLSv1.2 (IN), TLS handshake, Certificate (11): 20:37:11.908281 http.c:756 == Info: TLSv1.2 (IN), TLS handshake, Server key exchange (12): 20:37:11.908673 http.c:756 == Info: TLSv1.2 (IN), TLS handshake, Server finished (14): 20:37:11.908912 http.c:756 == Info: TLSv1.2 (OUT), TLS handshake, Client key exchange (16): 20:37:11.908923 http.c:756 == Info: TLSv1.2 (OUT), TLS change cipher, Change cipher spec (1): 20:37:11.908955 http.c:756 == Info: TLSv1.2 (OUT), TLS handshake, Finished (20): 20:37:11.918571 http.c:756 == Info: TLSv1.2 (IN), TLS change cipher, Change cipher spec (1): 20:37:11.918751 http.c:756 == Info: TLSv1.2 (IN), TLS handshake, Finished (20): 20:37:11.918832 http.c:756 == Info: SSL connection using TLSv1.2 / ECDHE-ECDSA-AES128-GCM-SHA256 20:37:11.918850 http.c:756 == Info: ALPN, server accepted to use h2 20:37:11.918860 http.c:756 == Info: Server certificate: 20:37:11.918882 http.c:756 == Info: subject: C=US; ST=California; L=San Francisco; O=GitHub, Inc.; CN=github.com 20:37:11.918892 http.c:756 == Info: start date: Mar 25 00:00:00 2021 GMT 20:37:11.918899 http.c:756 == Info: expire date: Mar 30 23:59:59 2022 GMT 20:37:11.918918 http.c:756 == Info: subjectAltName: host "github.com" matched cert's "github.com" 20:37:11.918932 http.c:756 == Info: issuer: C=US; O=DigiCert, Inc.; CN=DigiCert High Assurance TLS Hybrid ECC SHA256 2020 CA1 20:37:11.918940 http.c:756 == Info: SSL certificate verify ok. 20:37:11.918966 http.c:756 == Info: Using HTTP2, server supports multi-use 20:37:11.918999 http.c:756 == Info: Connection state changed (HTTP/2 confirmed) 20:37:11.919007 http.c:756 == Info: Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0 20:37:11.919098 http.c:756 == Info: Using Stream ID: 1 (easy handle 0x7fa6b002c400) 20:37:11.919131 http.c:703 => Send header, 0000000225 bytes (0x000000e1) 20:37:11.919142 http.c:715 => Send header: GET /kyanny/hello/info/refs?service=git-upload-pack HTTP/2 20:37:11.919148 http.c:715 => Send header: Host: github.com 20:37:11.919154 http.c:715 => Send header: User-Agent: git/2.32.0 20:37:11.919160 http.c:715 => Send header: Accept: */* 20:37:11.919166 http.c:715 => Send header: Accept-Encoding: deflate, gzip 20:37:11.919172 http.c:715 => Send header: Accept-Language: ja-JP, *;q=0.9 20:37:11.919191 http.c:715 => Send header: Pragma: no-cache 20:37:11.924139 http.c:715 => Send header: Git-Protocol: version=2 20:37:11.924203 http.c:715 => Send header: 20:37:11.927870 http.c:756 == Info: Connection state changed (MAX_CONCURRENT_STREAMS == 100)! 20:37:12.120119 http.c:703 <= Recv header, 0000000013 bytes (0x0000000d) 20:37:12.120162 http.c:715 <= Recv header: HTTP/2 200 20:37:12.120171 http.c:703 <= Recv header, 0000000026 bytes (0x0000001a) 20:37:12.120207 http.c:715 <= Recv header: server: GitHub Babel 2.0 20:37:12.120215 http.c:703 <= Recv header, 0000000059 bytes (0x0000003b) 20:37:12.120221 http.c:715 <= Recv header: content-type: application/x-git-upload-pack-advertisement 20:37:12.120257 http.c:703 <= Recv header, 0000000054 bytes (0x00000036) 20:37:12.120263 http.c:715 <= Recv header: content-security-policy: default-src 'none'; sandbox 20:37:12.120270 http.c:703 <= Recv header, 0000000040 bytes (0x00000028) 20:37:12.120278 http.c:715 <= Recv header: expires: Fri, 01 Jan 1980 00:00:00 GMT 20:37:12.120310 http.c:703 <= Recv header, 0000000018 bytes (0x00000012) 20:37:12.120347 http.c:715 <= Recv header: pragma: no-cache 20:37:12.120388 http.c:703 <= Recv header, 0000000053 bytes (0x00000035) 20:37:12.120434 http.c:715 <= Recv header: cache-control: no-cache, max-age=0, must-revalidate 20:37:12.120450 http.c:703 <= Recv header, 0000000023 bytes (0x00000017) 20:37:12.120462 http.c:715 <= Recv header: vary: Accept-Encoding 20:37:12.120473 http.c:703 <= Recv header, 0000000023 bytes (0x00000017) 20:37:12.120483 http.c:715 <= Recv header: x-frame-options: DENY 20:37:12.120496 http.c:703 <= Recv header, 0000000057 bytes (0x00000039) 20:37:12.120503 http.c:715 <= Recv header: x-github-request-id: E57F:0758:10C121B:13B9030:6130B767 20:37:12.120511 http.c:703 <= Recv header, 0000000002 bytes (0x00000002) 20:37:12.120517 http.c:715 <= Recv header: 20:37:12.123002 http.c:756 == Info: Connection #0 to host github.com left intact 20:37:12.123311 http.c:756 == Info: Couldn't find host github.com in the .netrc file; using defaults 20:37:12.123334 http.c:756 == Info: Found bundle for host github.com: 0x7fa69fd046b0 [can multiplex] 20:37:12.123350 http.c:756 == Info: Re-using existing connection! (#0) with host github.com 20:37:12.123359 http.c:756 == Info: Connected to github.com (13.114.40.48) port 443 (#0) 20:37:12.123378 http.c:756 == Info: Using Stream ID: 3 (easy handle 0x7fa6b002c400) 20:37:12.123410 http.c:703 => Send header, 0000000264 bytes (0x00000108) 20:37:12.123421 http.c:715 => Send header: POST /kyanny/hello/git-upload-pack HTTP/2 20:37:12.123460 http.c:715 => Send header: Host: github.com 20:37:12.123468 http.c:715 => Send header: User-Agent: git/2.32.0 20:37:12.123474 http.c:715 => Send header: Accept-Encoding: deflate, gzip 20:37:12.123483 http.c:715 => Send header: Content-Type: application/x-git-upload-pack-request 20:37:12.123492 http.c:715 => Send header: Accept: application/x-git-upload-pack-result 20:37:12.123511 http.c:715 => Send header: Git-Protocol: version=2 20:37:12.123581 http.c:715 => Send header: Content-Length: 164 20:37:12.123596 http.c:715 => Send header: 20:37:12.123634 http.c:756 == Info: We are completely uploaded and fine 20:37:12.315219 http.c:703 <= Recv header, 0000000013 bytes (0x0000000d) 20:37:12.315310 http.c:715 <= Recv header: HTTP/2 200 20:37:12.315328 http.c:703 <= Recv header, 0000000026 bytes (0x0000001a) 20:37:12.315340 http.c:715 <= Recv header: server: GitHub Babel 2.0 20:37:12.315353 http.c:703 <= Recv header, 0000000052 bytes (0x00000034) 20:37:12.315364 http.c:715 <= Recv header: content-type: application/x-git-upload-pack-result 20:37:12.315375 http.c:703 <= Recv header, 0000000054 bytes (0x00000036) 20:37:12.315387 http.c:715 <= Recv header: content-security-policy: default-src 'none'; sandbox 20:37:12.315398 http.c:703 <= Recv header, 0000000040 bytes (0x00000028) 20:37:12.315408 http.c:715 <= Recv header: expires: Fri, 01 Jan 1980 00:00:00 GMT 20:37:12.315422 http.c:703 <= Recv header, 0000000018 bytes (0x00000012) 20:37:12.315434 http.c:715 <= Recv header: pragma: no-cache 20:37:12.315448 http.c:703 <= Recv header, 0000000053 bytes (0x00000035) 20:37:12.315461 http.c:715 <= Recv header: cache-control: no-cache, max-age=0, must-revalidate 20:37:12.315476 http.c:703 <= Recv header, 0000000023 bytes (0x00000017) 20:37:12.315487 http.c:715 <= Recv header: vary: Accept-Encoding 20:37:12.315500 http.c:703 <= Recv header, 0000000023 bytes (0x00000017) 20:37:12.315512 http.c:715 <= Recv header: x-frame-options: DENY 20:37:12.315524 http.c:703 <= Recv header, 0000000057 bytes (0x00000039) 20:37:12.315537 http.c:715 <= Recv header: x-github-request-id: E57F:0758:10C1225:13B9041:6130B767 20:37:12.315549 http.c:703 <= Recv header, 0000000002 bytes (0x00000002) 20:37:12.315561 http.c:715 <= Recv header: 20:37:12.317253 http.c:756 == Info: Connection #0 to host github.com left intact 20:37:12.320097 http.c:756 == Info: Couldn't find host github.com in the .netrc file; using defaults 20:37:12.320124 http.c:756 == Info: Found bundle for host github.com: 0x7fa69fd046b0 [can multiplex] 20:37:12.320146 http.c:756 == Info: Re-using existing connection! (#0) with host github.com 20:37:12.320161 http.c:756 == Info: Connected to github.com (13.114.40.48) port 443 (#0) 20:37:12.320187 http.c:756 == Info: Using Stream ID: 5 (easy handle 0x7fa6b002c400) 20:37:12.320242 http.c:703 => Send header, 0000000264 bytes (0x00000108) 20:37:12.320254 http.c:715 => Send header: POST /kyanny/hello/git-upload-pack HTTP/2 20:37:12.320260 http.c:715 => Send header: Host: github.com 20:37:12.320266 http.c:715 => Send header: User-Agent: git/2.32.0 20:37:12.320272 http.c:715 => Send header: Accept-Encoding: deflate, gzip 20:37:12.320278 http.c:715 => Send header: Content-Type: application/x-git-upload-pack-request 20:37:12.320284 http.c:715 => Send header: Accept: application/x-git-upload-pack-result 20:37:12.320291 http.c:715 => Send header: Git-Protocol: version=2 20:37:12.320296 http.c:715 => Send header: Content-Length: 252 20:37:12.320302 http.c:715 => Send header: 20:37:12.320333 http.c:756 == Info: We are completely uploaded and fine 20:37:12.514738 http.c:703 <= Recv header, 0000000013 bytes (0x0000000d) 20:37:12.514809 http.c:715 <= Recv header: HTTP/2 200 20:37:12.514824 http.c:703 <= Recv header, 0000000026 bytes (0x0000001a) 20:37:12.514835 http.c:715 <= Recv header: server: GitHub Babel 2.0 20:37:12.514845 http.c:703 <= Recv header, 0000000052 bytes (0x00000034) 20:37:12.514854 http.c:715 <= Recv header: content-type: application/x-git-upload-pack-result 20:37:12.514864 http.c:703 <= Recv header, 0000000054 bytes (0x00000036) 20:37:12.514874 http.c:715 <= Recv header: content-security-policy: default-src 'none'; sandbox 20:37:12.514885 http.c:703 <= Recv header, 0000000040 bytes (0x00000028) 20:37:12.514900 http.c:715 <= Recv header: expires: Fri, 01 Jan 1980 00:00:00 GMT 20:37:12.514913 http.c:703 <= Recv header, 0000000018 bytes (0x00000012) 20:37:12.514927 http.c:715 <= Recv header: pragma: no-cache 20:37:12.514943 http.c:703 <= Recv header, 0000000053 bytes (0x00000035) 20:37:12.514957 http.c:715 <= Recv header: cache-control: no-cache, max-age=0, must-revalidate 20:37:12.514970 http.c:703 <= Recv header, 0000000023 bytes (0x00000017) 20:37:12.514987 http.c:715 <= Recv header: vary: Accept-Encoding 20:37:12.515004 http.c:703 <= Recv header, 0000000023 bytes (0x00000017) 20:37:12.515019 http.c:715 <= Recv header: x-frame-options: DENY 20:37:12.515035 http.c:703 <= Recv header, 0000000057 bytes (0x00000039) 20:37:12.515051 http.c:715 <= Recv header: x-github-request-id: E57F:0758:10C1236:13B9057:6130B768 20:37:12.515069 http.c:703 <= Recv header, 0000000002 bytes (0x00000002) 20:37:12.515105 http.c:715 <= Recv header: 20:37:12.518858 run-command.c:667 trace: run_command: git index-pack --stdin -v --fix-thin '--keep=fetch-pack 7182 on KensukenoMacBook-Pro.local' --check-self-contained-and-connected remote: Enumerating objects: 6, done. remote: Counting objects: 100% (6/6), done. remote: Compressing objects: 100% (3/3), done. remote: Total 6 (delta 0), reused 0 (delta 0), pack-reused 0 20:37:12.523223 http.c:756 == Info: Connection #0 to host github.com left intact 20:37:12.525878 git.c:455 trace: built-in: git index-pack --stdin -v --fix-thin '--keep=fetch-pack 7182 on KensukenoMacBook-Pro.local' --check-self-contained-and-connected Receiving objects: 100% (6/6), done. * Closing connection 0 20:37:12.534118 run-command.c:667 trace: run_command: git rev-list --objects --stdin --not --all --quiet --alternate-refs '--progress=Checking connectivity' 20:37:12.540699 git.c:455 trace: built-in: git rev-list --objects --stdin --not --all --quiet --alternate-refs '--progress=Checking connectivity'
Ubuntu 20.04.3 LTS 上の git 2.25.1 では以下のような出力になる。
$ GIT_CURL_VERBOSE=1 GIT_TRACE=1 git clone https://github.com/kyanny/hello 11:39:28.466447 git.c:439 trace: built-in: git clone https://github.com/kyanny/hello Cloning into 'hello'... 11:39:28.468728 run-command.c:663 trace: run_command: git-remote-https origin https://github.com/kyanny/hello * Couldn't find host github.com in the .netrc file; using defaults * Trying 52.192.72.89:443... * TCP_NODELAY set * Connected to github.com (52.192.72.89) port 443 (#0) * found 387 certificates in /etc/ssl/certs * ALPN, offering h2 * ALPN, offering http/1.1 * SSL connection using TLS1.3 / ECDHE_RSA_AES_128_GCM_SHA256 * server certificate verification OK * server certificate status verification SKIPPED * common name: github.com (matched) * server certificate expiration date OK * server certificate activation date OK * certificate public key: EC/ECDSA * certificate version: #3 * subject: C=US,ST=California,L=San Francisco,O=GitHub\, Inc.,CN=github.com * start date: Thu, 25 Mar 2021 00:00:00 GMT * expire date: Wed, 30 Mar 2022 23:59:59 GMT * issuer: C=US,O=DigiCert\, Inc.,CN=DigiCert High Assurance TLS Hybrid ECC SHA256 2020 CA1 * ALPN, server accepted to use h2 * Using HTTP2, server supports multi-use * Connection state changed (HTTP/2 confirmed) * Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0 * Using Stream ID: 1 (easy handle 0x561fca1e18c0) > GET /kyanny/hello/info/refs?service=git-upload-pack HTTP/2 Host: github.com user-agent: git/2.25.1 accept: */* accept-encoding: deflate, gzip, br accept-language: C, *;q=0.9 pragma: no-cache * Connection state changed (MAX_CONCURRENT_STREAMS == 100)! < HTTP/2 200 < server: GitHub Babel 2.0 < content-type: application/x-git-upload-pack-advertisement < content-security-policy: default-src 'none'; sandbox < expires: Fri, 01 Jan 1980 00:00:00 GMT < pragma: no-cache < cache-control: no-cache, max-age=0, must-revalidate < vary: Accept-Encoding < x-frame-options: DENY < x-github-request-id: E596:70D6:630C58:71FFF2:6130B7F1 < * Connection #0 to host github.com left intact 11:39:28.735999 run-command.c:663 trace: run_command: git fetch-pack --stateless-rpc --stdin --lock-pack --thin --check-self-contained-and-connected --cloning https://github.com/kyanny/hello/ 11:39:28.737966 git.c:439 trace: built-in: git fetch-pack --stateless-rpc --stdin --lock-pack --thin --check-self-contained-and-connected --cloning https://github.com/kyanny/hello/ * Couldn't find host github.com in the .netrc file; using defaults * Found bundle for host github.com: 0x561fca1e7bf0 [can multiplex] * Re-using existing connection! (#0) with host github.com * Connected to github.com (52.192.72.89) port 443 (#0) * Using Stream ID: 3 (easy handle 0x561fca1e18c0) > POST /kyanny/hello/git-upload-pack HTTP/2 Host: github.com user-agent: git/2.25.1 accept-encoding: deflate, gzip, br content-type: application/x-git-upload-pack-request accept: application/x-git-upload-pack-result content-length: 215 * We are completely uploaded and fine < HTTP/2 200 < server: GitHub Babel 2.0 < content-type: application/x-git-upload-pack-result < content-security-policy: default-src 'none'; sandbox < expires: Fri, 01 Jan 1980 00:00:00 GMT < pragma: no-cache < cache-control: no-cache, max-age=0, must-revalidate < vary: Accept-Encoding < x-frame-options: DENY < x-github-request-id: E596:70D6:630C64:71FFF9:6130B7F1 < remote: Enumerating objects: 6, done. remote: Counting objects: 100% (6/6), done. remote: Compressing objects: 100% (3/3), done. * 11:39:28.947007 run-command.c:663 trace: run_command: git unpack-objects --pack_header=2,6 Connection #0 to host github.com left intact remote: Total 6 (delta 0), reused 0 (delta 0), pack-reused 0 11:39:28.948537 git.c:439 trace: built-in: git unpack-objects --pack_header=2,6 Unpacking objects: 100% (6/6), 1.18 KiB | 1.18 MiB/s, done. 11:39:28.950322 run-command.c:663 trace: run_command: git rev-list --objects --stdin --not --all --quiet --alternate-refs '--progress=Checking connectivity' 11:39:28.951430 git.c:439 trace: built-in: git rev-list --objects --stdin --not --all --quiet --alternate-refs '--progress=Checking connectivity'
この差がプラットフォームの違いによるものなのか、Git クライアントのバージョンによるものなのかは調べていないが、Ubuntu で実行した時のログは curl -v の出力そのものなのに対して macOS 上で実行した時のログには http.c と出ているので、Git の新しめのバージョンから自前実装した HTTP クライアントを内蔵してそちらを使うようになった、とかかもしれない（以前は curl/libcurl を使っていた？）
